Loss of blocking dr yes, but you can build your character to hold aggro even in combat expertise and a shield. Remember, you get a 50% threat buff after intimidating, there are threat gear bonuses, and stance bonuses. At the moment, my paladin is capable of +135% bonus threat (100 divine righteousness, 15 tod set, 20 claw set). With this configuration, i need only a tiny head-start on even the best dps characters, and with the buff from the intimidate change (the actual buff, the threat generation bonus ater using the skill), I wouldn't even need a head start to hold aggro from Shade (at 235% bonus threat).
If you're a paladin, you could probably hold aggro with terrible gear even over far better equipped other players. With a fighter, you'll be 50% threat bonus behind (stance 50% instead of 100% righteousness) and you'll pretty much be able to hold vs anyone of equivalent equipment ability if you build to do so. Since the fighter can build both for twf alternatives when not tanking and more surely guarantee they hit every intimidate to gain the buff, they're in a pretty good place.
if you don't, well, then you're gonna suck at this.
I, for one, couldn't be gladder that the terrible play of intimiblock and never press other keys is gone. Fighters haven't had the option of threat tanking with max ac prior to this update. Paladins could do it (due to righteousness and much higher sword and board dps potential with the capstone) but fighters are just gaining the ability, basically.